The present disclosure relates to an objective lens for an endoscope and an endoscope including this objective lens for an endoscope.
Conventionally, endoscopes were used in medical fields to perform observation of the inside of a patient's body, treatment or the like. Japanese Patent No. 2596827 (Patent Document 1), Japanese Unexamined Patent Publication No. 2009-080413 (Patent Document 2), Japanese Patent No. 4265909 (Patent Document 3), Japanese Unexamined Patent Publication No. 2011-227380 (Patent Document 4), Japanese Patent No. 4999078 (Patent Document 5), Japanese Patent No. 5363354 (Patent Document 6) and Japanese Patent No. 5324321 (Patent Document 7) disclose lens systems usable as an objective lens for an endoscope. In these lens systems, a lens system consists of, in order from the object side, a front group having negative refractive power, a stop and a rear group having positive refractive power.